The present invention is directed to semiconductor radiation detectors, particularly to an improved semiconductor radiation spectrometer, and more particularly to a field engineered radiation spectrometer, based on engineering of the internal electrical field distribution via illumination by an optical light beam with a selected photon energy.
Semiconductor radiation detectors are utilized in a wide range of applications, such as medical imaging, environmental monitoring, baggage handling, materials sorting, nuclear materials detection, etc. The internal electric field distribution is an important key factor for the performance of semiconductor radiation detectors. Radiation detector researchers and manufacturers have made great effort to redesign or modify hardware for better detector performances, such as improved energy resolutions, sensitivities and signal to noise ratios. The hardware improvements, in essence, have been mainly aimed to redistribute the internal electric field distribution in a radiation detector to accomplish higher photo peak resolution and efficiency. Those detectors are generally known as single-charge collection devices, such as the coplanar electrodes, and the three-electrode detectors, etc. For such coplanar electrode detectors, see P.N. Luke, IEEE Trans. Nucl. Sci. 42,207 (1995), xe2x80x9cUnipolar Charge Sensing With Coplanar Electrodes-Application To Semiconductor Detectors;xe2x80x9d and for the three-electrode detectors, see C.L. Lingren et al., IEEE Trans. Nucl. Sci. (1998), xe2x80x9cCadmiun-Zinc-Telluride, Multiple-Electrode Detectors Achieve Good Energy Resolution With High Sensitivity At Room Temperature.xe2x80x9d While these coplanar and three electrode device structures have improved the detector sensitivity, these structures are usually complex, difficult and expensive to manufacture. Thus, there is a need for a sensitive, less expensive semiconductor radiation detector.
The present invention provides a solution to the above-mentioned need by providing an improved semiconductor radiation detector which involves engineering the internal electric field through an internal infrared light source. The invention is field engineered radiation spectrometer (FERADS), which uses an optical beam with a selected photon energy to illuminate the detector and engineer the internal electric field. Tests have shown that different light beam intensities or photon energies produce different distributions of the internal electric field, thus radiation detector performance can be optimized.
It is an object of the present invention to provide an improved semiconductor radiation detector.
A further object of the invention is to provide a field engineered radiation spectrometer.
A further object of the invention is to provide a method for improving semiconductor radiation detectors by engineering the internal electrical field through an external infrared light source.
Another object of the invention is to provide a method for improving semiconductor radiation detectors by illuminating the detector with an optical light beam with a selected photon energy.
Another object of the invention is to provide a method for engineering the internal electric field of a semiconductor radiation detector by controlling light beam intensities or photon energies of an optical light beam which illuminates the detector.
Other objects and advantages of the present invention will become apparent from the following description and accompanying drawings. Basically, the invention is a field engineered radiation spectrometer, and more particularly the invention involves improved semiconductor radiation detectors obtained by engineering the internal electrical field through an external infrared light source. By applying a bias voltage across a planar semiconductor radiation detector and illuminating the detector with an optical light beam with a selected photon energy, the internal electric field can be engineered. Tests have shown that different light beam intensities or photon energies produce different distributions of the internal electric field. By the method of this invention, the width of the electric field can be fine-tuned by changing the optical beam intensity and wavelength, so that the radiation detector performance can be optimized. The improved semiconductor radiation detector is portable, small size, and operates at room temperature. This invention enables stacking of many smaller detectors, vertically and horizontally, to further increase the overall detector efficiency. The optical method of this invention provides a simple, nondestructive, contactless, and less costly approach to produce improved semiconductor radiation detectors.